1. Field of the Invention
The present invention relates to a method of forming a pattern that is suitable for use in, for example, a semiconductor production process for an IC or the like, a circuit board production process for a liquid crystal, a thermal head or the like and other photofabrication lithography processes, and relates to an actinic-ray- or radiation-sensitive resin composition for use in the pattern forming method and an actinic-ray- or radiation-sensitive film. More particularly, the present invention relates to a method of forming a pattern that is suitable for the exposure to light by means of a KrF exposure apparatus, an electron beam exposure apparatus or an EUV exposure apparatus, and relates to an actinic-ray- or radiation-sensitive resin composition for use in the pattern forming method and an actinic-ray- or radiation-sensitive film.
2. Description of the Related Art
Since the development of the resist for a KrF excimer laser (248 nm), an image forming method based on chemical amplification has been employed as a resist image forming method in order to compensate for any sensitivity decrease caused by light absorption. A positive image forming method based on chemical amplification will be described by way of example. In this image forming method, the acid generator contained in exposed areas is decomposed upon exposure to light, such as an excimer laser, electron beams or an extreme ultraviolet light, to thereby generate an acid. In the stage of the bake after the exposure (Post-Exposure Bake: PEB), the generated acid is utilized as a reaction catalyst so that alkali-insoluble groups are converted to alkali-soluble groups. Thereafter, the exposed areas are removed by an alkali developer.
For use in the above method, various alkali developers have been proposed. For example, an aqueous alkali developer containing 2.38 mass % TMAH (aqueous solution of tetramethylammonium hydroxide) is universally used.
In another aspect, not only the currently mainstream positive type but also negative chemically amplified resist compositions for use in the pattern formation by alkali development are being developed (see, for example, patent references 1 to 4). This reflects the situation in which in the production of semiconductor elements and the like, while there is a demand for the formation of patterns with various shapes, such as a line, a trench and a hole, there exist patterns whose formation is difficult with the use of current positive resists.
In recent years, also, a pattern forming method using a negative developer, namely, a developer comprising an organic solvent is being developed (see, for example, patent references 5 to 7). For example, patent reference 7 discloses a pattern forming method comprising the operations of applying onto a substrate a positive resist composition that when exposed to actinic rays or radiation, increases its solubility in a positive developer and decreases its solubility in a negative developer, exposing the applied resist composition to light and developing the exposed resist composition with a negative developer. This method realizes the stable formation of a high-precision fine pattern.
However, it has been found that the possibility of residue defect occurrence is high when the development is performed with a developer comprising an organic solvent.
Moreover, the most advanced pattern formation being developed in recent years comprises liquid-immersion exposure by means of an ArF excimer laser so as to realize the formation of a pattern of high resolution. Resins containing an aromatic ring or a double bond absorb ArF light, namely, 193 nm light, so that satisfactory transmission cannot be ensured with the use thereof. Accordingly, the resin to be incorporated in the resist composition for ArF is quite often comprised of an aliphatic compound. Therefore, designing for rendering an Onishi parameter low is difficult, and a poor etching resistance is likely to be exhibited.